A network discovery system is a type of network management system that investigates a data network and discovers a topology of network devices that make up that network. IBM® Tivoli® Network Manager IP is a type of network discovery system for ISO layers 2 and 3 (the “IP layers”). IBM® Tivoli® Network Manager TN is another type of network discovery system for ISO layer 1 (the “transport layer” or “physical layer”).
In a network of network devices, some devices have multiple IP addresses. One of the IP addresses may be the primary IP address used to identify and control the device, while the other IP addresses may be used for secondary purposes. These secondary IP addresses are referred to herein as “special IP addresses.” Special IP addresses may be system-defined, and can be any type of IP address, including some operational IP addresses.
One type of special IP address is a virtual IP address (sometimes called an “imaginary IP address” or “secret IP address”). A virtual IP address may be used in the operation of a device, but does not normally show up in the device's IP address table when such a request is made.
Another type of special IP address is an out-of-band IP address that has restricted access, normally limited to the systems within the network operations center (“NOC”), such as the network management software. An out-of-band IP address is generally inaccessible to customers on the network. Other types of special IP addresses may be defined by the user as management IP addresses according to other properties.